This is an observational study which will evaluate the efficacy of the serratus anterior plane block for treating pain and respiratory capacity in patients with multiple rib fractures. When resources are available for a SAPB to be performed, patients will receive this block in addition to traditional pain medications, while at other times, patients will receive traditional pain medications only.

Pain management by systemic analgesics and by nerve blocks are both standard of care and used in Emergency Department (ED) depending on the resources available. Not all ED physicians are trained or comfortable with the serratus anterior nerve block and thus it is not always available to patients and is provider dependent.

This is an observational study where patients with multiple rib fractures will receive either a serratus anterior plane block (SAPB) in addition to traditional forms of pain control when providers trained to perform the block are available, or will receive traditional forms pain control if trained personnel are not available. In addition to the serratus anterior plane block, standard forms of pain control in the Stanford Emergency Department include: oral or parenteral acetaminophen, oral or parenteral NSAIDs, oral or parenteral opiates, parenteral lidocaine, and parenteral ketamine.

Retrospective evaluation of the allocation of patients to either nerve block or no nerve block will be dictated by physician ability, time and resources to do the block. The efficacy of the block will be evaluated by serial measurements of pain score and respiratory capacity.

Inclusion Criteria:

1. Age greater or equal to 18 years of age
2. Presentation to Stanford University Hospital Emergency Department within 12 hours of a traumatic incident
3. Three or more anterior and/or lateral unilateral rib fractures diagnosed by CT
4. GCS 15, with the ability to discern and describe pain from rib fractures and give consent
5. Presentation to the Emergency Department between 7am and 11pm (for identification by research assistants)

Exclusion Criteria:

1. Posterior rib fractures
2. Bilateral rib fractures
3. Sternal fracture
4. Known allergy to local anesthetics
5. Pregnancy
6. Significant coagulopathy
7. Hemodynamic instability

Participants will be patients who are 18 years and older (of all genders and ethnic backgrounds) presenting to the Stanford University Emergency Department with multiple, acute, unilateral, antero-lateral rib fractures who meet inclusion/exclusion criteria